Unit 1 lesson 4 Flashcards
1
Q
What is the purpose of the malting process?
A
To modify the barley endosperm, ensuring starch is accessible to enzymes during mashing.
2
Q
What are the three main stages of malting?
A
- Steeping
- Germination
- Kilning
3
Q
What moisture level does steeping increase the grain from and to?
A
From 10-12% to around 45%.
4
Q
At what moisture level does germination start?
A
Above 30%.
5
Q
What happens if moisture levels exceed 46% during steeping?
A
It can negatively affect germination.
6
Q
What is the ideal moisture level for germination?
A
Between 43-46%.
7
Q
How does temperature affect water uptake in barley grains?
A
Water uptake is faster at higher temperatures.
8
Q
What is the germinative capacity (GC) test?
A
A test that involves cutting 100 grains and staining them to check viability.
9
Q
What does a pink stain indicate in the GC test?
A
Living embryos.
10
Q
What is the germinative energy (GE) test?
A
A test to measure rootlet growth in wetted grains over three days.
11
Q
What is water sensitivity in grains?
A
A condition where grains do not germinate in excess water.
12
Q
How is water sensitivity calculated?
A
Water sensitivity = number of germinated grains in 4 mL test - number of germinated grains in 8 mL test.
13
Q
What role does gibberellic acid (GA) play in malting?
A
Stimulates enzyme production in the aleurone layer.
14
Q
Name two enzymes synthesized de novo in response to GA.
A
- α-Amylase
- limit dextrinase
- Endoproteases
15
Q
What is the main advantage of flat-bottom steeps?
A
They can be designed for multiple duties.
16
Q
What must barley for malting be free from?
A
- Stones
- Metal
- Foreign seeds
- Dust
- Broken grains
17
Q
What is the purpose of ventilation in steeping vessels?
A
To provide oxygen and remove CO2 and heat.
18
Q
What is the ideal condition for barley hydration?
A
Even hydration of all grains.
19
Q
True or False: Dormancy naturally breaks with time.
A
True.
20
Q
Fill in the blank: The first root that appears after 24 hours is called the ______.
A
chit.
21
Q
What surrounds the cone section in a conical steep to stop barley from escaping?
A
Wedge wire screen
The wedge wire screen allows water to drain while retaining the barley.
22
Q
How is aeration achieved in flat-bottom steep vessels?
A
Through aeration nozzles beneath the perforated floor and on the vessel sides
This facilitates air movement and mixing of the grain.
23
Q
In conical steeps, how is aeration accomplished?
A
Using nozzles or an aeration ring in the cone of the vessel
An external fan may also draw air through the grain bed.
24
Q
What are the three purposes of adding fresh air during the air rest?
A
- Removal of CO2
- Removal of heat
- Provision of oxygen
Fresh air is crucial for maintaining aerobic respiration in barley.
25
What is steeping?
Not simply immersing grain in water; it involves submerging and draining the grain at set periods
## Footnote
Steeping is a controlled process essential for malting.
26
What should the water used for steeping be free of?
* Pathogens
* Dissolved organic material
* Heavy metals
* High chlorine levels
## Footnote
Clean, potable water is critical for successful steeping.
27
What factors influence the appropriate steeping programme?
* Varietal purity
* Current moisture level
* Germinative energy
* Germinative capacity
* Water sensitivity
* Total nitrogen
## Footnote
These factors determine the malting ability of the grain.
28
What is the typical temperature range for the steeping stage?
12-15°C
## Footnote
This temperature range is optimal for the first immersion stage.
29
What should be the maximum temperature of grain during an air rest?
21-23°C
## Footnote
Exceeding this temperature can damage the grain and impair enzyme systems.
30
What is a characteristic of water sensitive barley during steeping?
It can fail to germinate if immersion stands are too long
## Footnote
Water sensitive barley requires shorter immersions followed by longer air rests.
31
What happens if too much water is given too quickly to grain?
The grain becomes saturated and is slower to progress to chitting
## Footnote
Proper water management is crucial for successful germination.
32
What is the typical range for water and air temperatures during steeping?
9-16°C
## Footnote
Each barley variety has an optimum temperature for growth within this range.
33
What is an Acrospire?
The shoot that grows from the embryo of the barley grain during germination. Its length is an indicator of the extent of modification.
34
What is the Aleurone Layer?
The outermost layer of the endosperm in barley, responsible for producing enzymes during germination.
35
Define Amylase.
An enzyme that breaks down starch into sugars. There are two main types: α-amylase and β-amylase.
36
What is the Break Point in kilning?
The stage in kilning when the moisture on the surface of the grain has been evaporated, causing the air-off temperature to rise.
37
What composes the Cell Wall in barley?
Primarily composed of β-glucans and pentosans.
38
What is the Endosperm in barley?
The starchy interior of the barley grain, which is broken down during malting to provide fermentable sugars.
39
What is an Enzyme?
A protein that catalyzes biochemical reactions. Key enzymes in malting include amylases, proteases, and glucanases.
40
What is Forced Drying in kilning?
The second phase of kilning where moisture is removed from the center of the grain at higher temperatures.
41
What occurs during Free Drying in kilning?
The initial phase of kilning where moisture on the surface of the grain is removed at lower temperatures.
42
Define Germination.
The stage in malting where the barley grain begins to sprout, activating enzymes that modify the endosperm.
43
What is Germinative Capacity (GC)?
A measure of the percentage of barley grains that are alive and capable of germination.
44
What is Germinative Energy (GE)?
A measure of the percentage of barley grains that germinate under optimal conditions.
45
What is Gibberellic Acid (GA)?
A plant hormone produced by the embryo that stimulates enzyme production during germination.
46
What is Kilning?
The final stage of malting where the malt is dried to a moisture level of 3-6%, stopping germination and developing flavor and color.
47
What is Lipoxygenase (LOX)?
An enzyme in malt that can cause off-flavors in beer. It is controlled by higher temperatures during kilning.
48
What is the Maillard Reaction?
A chemical reaction between amino acids and reducing sugars that gives malt its color and flavor during kilning.
49
Define Modification in malting.
The sum of the changes that occur in the barley grain during malting, including the breakdown of cell walls and proteins.
50
What is Nitrosodimethylamine (NDMA)?
A toxic compound that can form during kilning. It is controlled by using indirect heating methods.
51
What is the Protein Matrix?
The network of proteins within the endosperm that surrounds the starch granules.
52
What is Respiration in the context of malting?
The metabolic process during steeping and germination where the grain converts glucose to energy, CO2, and heat.
53
What is Water Sensitivity in barley grains?
A condition where barley grains fail to germinate in excess water due to microorganism competition for oxygen.
54
What is the Wanderhaufen System?
A germination system where the germinating malt is moved along an extended box in steps, allowing for controlled airflow and temperature.
55
What is the initial moisture level required for grain germination in the malting process?
Approximately 45%
## Footnote
The process begins with steeping, increasing moisture from storage levels of around 10-12%.
56
What is the purpose of steeping in the malting process?
To uniformly hydrate the grain and initiate germination
## Footnote
Steeping is crucial for ensuring all grains are equally hydrated for optimal germination.
57
What by-products are produced during the respiration of grain in the steeping process?
Carbon dioxide, water, and heat
## Footnote
This process converts glucose to energy for the grain.
58
What can happen if the grain is not uniformly hydrated during steeping?
It can lead to unmalted or under-modified grains, reducing brewing yields
## Footnote
Uneven hydration affects the quality and efficiency of brewing.
59
How does water enter the grain during the malting process?
Through the micropyle
## Footnote
Water moves from high concentration areas to lower concentration areas.
60
What role does gibberellic acid (GA) play in the malting process?
It stimulates enzyme production necessary for breaking down storage materials in the endosperm
## Footnote
GA is crucial for the activation of various enzymes during malting.
61
Name three enzymes synthesized in response to gibberellic acid during malting.
* α-amylase
* Limit dextrinase
* Endoproteases
## Footnote
These enzymes are essential for the conversion of stored materials into usable forms.
62
What types of vessels are used in the steeping process?
* Conical steeps
* Flat-bottom steeps
## Footnote
Different designs serve various purposes in the steeping and germination process.
63
What is a steely grain in the context of barley?
A grain with a higher protein content that absorbs water more slowly
## Footnote
In contrast, mealy grains absorb water quickly due to their sponge-like texture.
64
What triggers germination in barley grains?
An increase in moisture
## Footnote
It is crucial to ensure the entire endosperm is hydrated.
65
What is the ideal moisture level for germination in barley?
43-46%
## Footnote
This moisture level is necessary to avoid uneven modification.
66
What factors influence water uptake in barley grains?
* Temperature
* Grain size
* Protein content
* Husk integrity
67
What type of grains absorb water faster, steely or mealy?
Mealy grains
## Footnote
Mealy grains are more like a bath sponge.
68
What test is commonly used to check the germinative capacity (GC) of barley?
GC peroxide test
## Footnote
This involves soaking grains in hydrogen peroxide and counting germinated grains.
69
What does the germinative energy (GE) test measure?
The ability of the grain to germinate
## Footnote
The difference between GC and GE results indicates dormancy.
70
What is water sensitivity in grains?
A phenomenon where grains do not germinate in excess water
## Footnote
It occurs due to microorganisms competing for oxygen.
71
What hormone plays a crucial role in the steeping process?
Gibberellic acid (GA)
## Footnote
GA stimulates enzyme production essential for breaking down storage materials.
72
What are the two types of steeping vessels mentioned?
* Conical steeps
* Flat-bottom steeps
73
What is a key function of steeping vessels?
To hydrate the grain, remove carbon dioxide, provide oxygen, and enable air rests.
74
What is the role of a barley mixer in the steeping process?
To combine dry barley with water for less damaging slurry
## Footnote
This method produces less dust.
75
What factors influence the steeping program?
* Barley variety
* Season
* Time after harvest
* Germinative energy
* Germinative capacity
* Water sensitivity
* Total nitrogen
76
What factors influence the appropriate steeping program for barley?
Factors include varietal purity, current moisture level, germinative energy, germinative capacity, water sensitivity, and total nitrogen.
77
How does the storage time after harvest affect barley's malting ability?
Grain can require less steeping and germination after a few months than in the first few weeks after harvest.
78
What is the recommended steeping program for water-sensitive barley?
Shorter immersions followed by longer air rests.
79
What temperature must not be exceeded during air rests to avoid damaging the embryo?
23°C.
80
What relative humidity is essential during the air rests for barley?
> 95% relative humidity.
81
What is the typical temperature range for water and air during barley germination?
9-16°C.
82
What is the main function of enzymes during germination?
They break down the endosperm cell walls and starch granules.
83
What role does limit dextrinase play in starch conversion?
It allows amylopectin to be converted to sugars.
84
What does excess fertilizer use lead to in barley grains?
High-density protein matrices that are hard and steely.
85
What are some effects of using commercially produced GA?
* Increases extract
* Increases soluble proteins
* Increases α-amylase levels
* Decreases germination time
* Decreases color
86
What are traditional germination systems for barley?
Floor maltings where barley is spread in a shallow bed on a concrete floor.
87
What modern features do germination vessels include?
* Stainless steel wedge-wire or perforated floor
* Means of turning the grain bed
* Pressure fan with air humidification unit
* Recirculation ducts
88
How is bed moisture maintained during germination?
By controlling relative air humidity and spraying the bed.
89
What is the maximum percentage of recirculated air used to control air-on temperatures?
No more than 80%.
90
What is the main consequence of respiration in the grain bed?
It increases the bed's temperature and reduces the grain's moisture.
91
How much moisture can grain lose per day during active growth?
Roughly 0.5% moisture per day.
92
What moisture content should be maintained during the highest rate of respiration?
43-46% moisture.
93
What is measured during the germination process to determine grain modification?
Moisture level and acrospire growth
## Footnote
Acrospire growth indicates the extent of modification in the grain.
94
What solution is used in the acrospire growth test?
Copper sulphate solution
## Footnote
This solution makes the acrospires visible through the husk.
95
How is the length of the acrospires categorized?
0-1/4, 1/4-1/2, 1/2-3/4, 3/4-1, and >1
## Footnote
This categorization indicates the extent of modification.
96
What does it indicate if the majority of acrospires are in the 0-1/4 range?
They are either dead or growing slowly
## Footnote
This implies poor modification of the grain.
97
What is the appearance of correctly modified starchy endosperm when rubbed between fingers?
Looks like chalk on the fingers
## Footnote
This indicates proper modification during germination.
98
How long does barley typically spend in the germination vessel?
Four to six days
## Footnote
This duration is standard for proper germination.
99
What can over-modification of grain reduce?
Extract levels
## Footnote
This occurs because starch is lost to embryo growth.
100
What issues can arise from over-modified grain during milling?
Dust losses and finer grist than required
## Footnote
This affects the wort separation system.
101
What problems can under-modified grain cause in brewing?
Issues in brewhouse and filtration
## Footnote
This is due to undegraded β-glucans.
102
What is the final stage of malting?
Kilning
## Footnote
This stage is also the most energy-intensive.
103
What is the required moisture level during kilning?
3-6%
## Footnote
This moisture level is crucial for proper malt quality.
104
What happens to bed depth during the malting process?
It reduces from over 3 meters in steeping to around 0.75 meters in kilning
## Footnote
This minimizes differences in malt quality.
105
What is the energy consumption percentage of kilning in the malting process?
75-85%
## Footnote
This highlights the energy-intensive nature of kilning.
106
What happens to enzymes in malt when exposed to high temperatures during kilning?
They are lost
## Footnote
Longer exposure leads to more enzyme loss.
107
What is the role of low temperatures in the initial stages of kilning?
Help preserve enzymes
## Footnote
This is crucial for enzyme functionality in brewing.
108
What reactions occur when sugars and amino acids are exposed to heat during kilning?
They form Maillard or non-enzymatic browning products
## Footnote
These reactions contribute to malt color and flavor.
109
What undesirable flavor is associated with dimethyl sulphide (DMS)?
Vegetable-, cabbage-, or sweetcorn-like flavor
## Footnote
This flavor is considered undesirable in some beers.
110
What precursor forms DMS during kilning?
S-methylmethionine (SMM)
## Footnote
SMM splits into DMS and DMSO when heated.
111
What compound is formed during kilning that is toxic and water-soluble?
Nitrosodimethylamine (NDMA)
## Footnote
NDMA formation is linked to hordenine reacting with nitrogen oxides.
112
What is the primary method used in modern kilns to reduce NDMA formation?
Indirect heating methods
## Footnote
This method is safer compared to direct-fired kilns.
113
What enzyme in malt can cause off-flavors in beer?
Lipoxygenase (LOX)
## Footnote
Higher temperatures during kilning can remove LOX.
114
What design improvements have been made in modern kilns?
Single-floor designs and more efficient air circulation
## Footnote
These changes enhance energy efficiency.
115
What happens to the malt bed as the grain dries out?
It becomes more permeable to air
## Footnote
This aids in the drying process.
116
What are the three distinct phases of kilning control?
Free drying, forced drying, and curing
## Footnote
Each phase has specific temperature and airflow requirements.
117
What temperature should malt be cooled to after curing?
Around 30°C
## Footnote
This helps prevent additional color pick-up.
